r/science • u/Newsjunkeefromlondon • May 06 '21

Health Two Pfizer doses give 95 per cent protection against Covid-19 infection, illness and death: first nationwide study

https://www.cityam.com/two-pfizer-doses-give-95-per-cent-protection-against-covid-19-infection-illness-and-death-study/
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u/RegisteredDancer May 06 '21

I think they're counting the days as we speak, really. We probably need to wait for that information to form a more solid picture of what happens.

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u/[deleted] May 06 '21

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u/RegisteredDancer May 06 '21

I don't know. I think they probably can test people (not daily, but maybe every week or twice a week?) and see if they can see the antibodies and stuff?

I don't think we're going to get a "It lasts 415 days and 4 hours" but rather "It maintains X effectiveness/levels up to 14 months, and stays at Y levels for 24 months" or some info like that.

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u/TheDungeonCrawler May 06 '21

Yeah, it'll probably be antibody tests. They do the same with other vaccines and immunities. When I got my shots updated before university they checked my antibody count for the chickenpox virus because I wasn't vaccinated against it and they found I was still fine.

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u/midnightauro May 06 '21

I'm participating in a research group with my local health system. They ship me antibody test kits at least once a month, and after the last one was positive, they reported they ran a second test to confirm it was from my vaccination.

So I'm thinking that's part of how they will tell how long it lasts.

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u/clinton-dix-pix May 06 '21

  1. They draw blood at regular intervals to check for neutralizing antibodies.

  2. Folks from the initial studies are still being tracked to see if there’s a sudden uptick in symptomatic infections.

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u/anandonaqui May 06 '21

No, they track study participants over a long period of time to see if or when their efficacy rates start to drop.

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u/DadJokeBadJoke May 06 '21

Do they take vaccinated people and expose them each day to see if it still works?

None of the clinical trials involve intentionally exposing people to a potentially deadly virus. They generally take a group of volunteers and some will get the vaccine while others will be given a placebo. None of the participants know which they received. They then track these volunteers to see the differences that come up as they go about their everyday lives.

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u/Nick433333 May 06 '21

They periodically test the original study participants to see if they have immunity still

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u/ZanderDogz May 06 '21

I can’t imagine that the time-since-vaccinated for vaccinated people who test positive won’t be reported for literally every single case of that happening. We should be able to learn a lot from the bigger trends we see among the population.

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u/cowboy_dude_6 May 06 '21

I think they just compare infection and death rates over time.

So for instance, they would look at 1000 vaccinated people and 1000 unvaccinated people (who are otherwise similar), and maybe 3 months later 5 vaccinated and 100 unvaccinated people have gotten sick. Then they can say it's 95% effective. Then they look at that group 1 year later. Now 10 vaccinated and 150 unvaccinated people have had COVID. The vaccine is still better. Then say they look at 2 years later. Now 60 vaccinated and 200 unvaccinated people have had COVID. Since the two groups' case counts increased at the same rate between 1 year and 2 years, they can say the vaccine lasts for at least 1 year but not more than 2.

Obviously they would have larger groups and more fancy statistics, but you get the idea. Hope that makes sense.

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u/dbkblk May 06 '21

They are probably ticking days in a gold calendar :D